Skip to Main Content
Skip Nav Destination
GEOREF RECORD

Inverse modeling constrained by potential field data, petrophysics, and improved geologic mapping; a case study from prospective northwest Tasmania

Esmaeil Eshaghi, Anya M. Reading, Michael Roach, Mark Duffett, Daniel Bombardieri, Matthew J. Cracknell, John L. Everard, Grace Cumming and Stephen Kuhn
Inverse modeling constrained by potential field data, petrophysics, and improved geologic mapping; a case study from prospective northwest Tasmania
Geophysics (July 2020) 85 (5): K13-K26

Abstract

The Heazlewood-Luina-Waratah area is a prospective region for minerals in northwest Tasmania, Australia, associated with historically important ore deposits related to the emplacement of granite intrusions and/or ultramafic complexes. The geology of the area is poorly understood due to the difficult terrain and dense vegetation. We have constructed an initial high-resolution 3D geologic model of this area using constraints from geologic maps and geologic and geophysical cross sections. This initial model is improved upon by integrating results from 3D geometry and physical property inversion of potential field (gravity and magnetic) data, petrophysical measurements, and updated field mapping. Geometry inversion reveals that the Devonian granites in the south are thicker than previously thought, possibly connecting to deep sources of mineralization. In addition, we identified gravity anomalies to the northeast that could be caused by near-surface granite cupolas. A newly discovered ultramafic complex linking the Heazlewood and Mount Stewart Ultramafic Complexes in the southwest also has been modeled. This implies a greater volume of ultramafic material in the Cambrian successions and points to a larger obducted component than previously thought. The newly inferred granite cupolas and ultramafic complexes are targets for future mineral exploration. Petrophysical property inversion reveals a high degree of variation in these properties within the ultramafic complexes indicating a variable degree of serpentinization. Sensitivity tests suggest maximum depths of 2-3 km for the contact aureole that surrounds major granitic intrusions in the southeast, whereas the Heazlewood River complex is likely to have a deeper source up to 4 km. We have demonstrated the value of adding geologic and petrophysical constraints to 3D modeling for the purpose of guiding mineral exploration. This is particularly important for the refinement of geologic structures in tectonically complex areas that have lithology units with contrasting magnetic and density characteristics.


ISSN: 0016-8033
EISSN: 1942-2156
Coden: GPYSA7
Serial Title: Geophysics
Serial Volume: 85
Serial Issue: 5
Title: Inverse modeling constrained by potential field data, petrophysics, and improved geologic mapping; a case study from prospective northwest Tasmania
Affiliation: ExploreGeo, Wangara, West. Aust., Australia
Pages: K13-K26
Published: 20200728
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 60
Accession Number: 2020-060754
Categories: Applied geophysicsEconomic geology, geology of ore deposits
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sect., 2 tables, sketch map
S43°40'00" - S39°30'00", E143°49'60" - E148°30'00"
Secondary Affiliation: University of Tasmania, AUS, AustraliaMineral Resources Tasmania, AUS, Australia
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2020, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by Society of Exploration Geophysicists, Tulsa, OK, United States
Update Code: 202017
Close Modal

or Create an Account

Close Modal
Close Modal